function [A, B, E, H, N] = readD()
    folder = 'FitzHughNagumo/';
    filenames = {'FHN.A', 'FHN.B', 'FHN.E', 'FHN.H', 'FHN.N'};
    A = [];
    B = [];
    E = [];
    H = [];
    N = [];
    
    for i = 1:length(filenames)
        data = load([folder, filenames{i}]);
        
        size = data(1, 1:2)';
        data(1, :) = [];
        
        switch i
            case 1
                A = sparse(data(:, 1), data(:, 2), data(:, 3), size(1), size(2));
            case 2
                B = sparse(data(:, 1), data(:, 2), data(:, 3), size(1), size(2));
            case 3
                E = sparse(data(:, 1), data(:, 2), data(:, 3), size(1), size(2));
            case 4
                H = sparse(data(:, 1), data(:, 2), data(:, 3), size(1), size(2));
            case 5
                N = sparse(data(:, 1), data(:, 2), data(:, 3), size(1), size(2));
        end
    end
end
